Systems, methods, and test kits for analyte variation detection

ABSTRACT

Systems, methods, and test kits for monitoring and detecting variation in an analyte level in a fluid sample from an individual variation using a uniquely determined analyte threshold value. In one implementation, luteinizing hormone is the monitored analyte and is compared with the determined threshold value to predict the onset of ovulation for the individual.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a divisional of U.S. patent application Ser.No. 13/229,156, entitled “SYSTEMS, METHODS, AND TEST KITS FOR ANALYTEVARIATION DETECTION,” filed on Sep. 9, 2011, which is hereby expresslyincorporated by reference in its entirety. Furthermore, any and allpriority claims identified in the Application Data Sheet, or anycorrection thereto, are hereby incorporated by reference under 37 C.F.R.§ 1.57

FIELD

The present invention relates to the field of analyte detection systemsand methods, with particular applicability to predicting the timing ofovulation.

BACKGROUND

Analysis of the levels of hormone in an individual can provide importantand helpful prognostic information. For example, detected hormone levelsmay enable an evaluation of a woman's health concerns such as fertility,pregnancy and menopause. One component in evaluating a woman's fertilitystatus is assessing her ovulatory function. The average menstrual cyclegenerally lasts 28 days, during which there is a transition from thefollicular phase to the luteal phase. The follicular phase of themenstrual cycle begins on the first day of menstruation and is followedby a rise in follicle-stimulating hormone (FSH), luteinizing hormone(LH) and estrogen, the latter promoting the maturation of a follicle.Once estrogen levels reach an optimal concentration and duration, thepituitary gland is prompted to release a large burst of LH secretionthat significantly raises the concentration of circulating LH in blood.This rise in circulating hormone is known as LH surge. This surge in LHmarks the transition to the luteal phase of the cycle, resulting infinal maturation of the follicle, release of a mature oocyte from thefollicle (ovulation), and corpus luteum formation. After ovulation,estrogen levels continue to rise along with an increase in progesteronelevels in order to prepare the endometrium for implantation. Iffertilization of the oocyte occurs, the implantation of the fertilizedoocyte within the uterine endometrial lining triggers production ofhuman chorionic gonadotropins (hCG) that maintains the corpus luteum andprogesterone production. However in the absence of fertilization, thecorpus luteum deteriorates resulting in a decrease in the levels of bothestrogen and progesterone, and sloughing of the endometrial liningthereby marking the onset of the next cycle.

In assessing ovulatory function, daily measurements of LH levels may beused to predict the timing of ovulation. The rise in blood LH may occur˜24-36 hours prior to ovulation.

Measurements of serum progesterone levels 18 to 24 days after the onsetof menses or seven days before the next cycle may be used to confirmwhether ovulation had occurred. In the event of a confirmed pregnancy,serum progesterone levels may be utilized to assess nonviablepregnancies, e.g., ectopic pregnancy or spontaneous abortion(miscarriage). In pregnant individuals, a serum progesterone value of≥25 ng/ml is 98% of the time associated with a viable pregnancy, while avalue of <5 ng/ml identifies a nonviable pregnancy.

Another component in evaluating a woman's fertility status may beassessing the functioning potential of the ovary with respect to thequantity and quality of the oocytes within the ovary, commonly referredto as ovarian reserve. An acceleration of follicular loss is prevalentin the last 10-15 years before menopause. This loss correlates with asubtle increase in FSH. One test that may be used to assess ovarianreserve is the Day 3 FSH test. This test determines the level of FSH oncycle day three during which estrogen level is expected to be low. Acycle day three FSH level <10 IU/L is suggestive of adequate ovarianreserve, whereas an FSH level >25 IU/L is associated with a chance ofpregnancy close to zero during ovulation induction.

A woman's fertility may also be affected by fluctuations in thyroidgland function. The measurement of thyroid-stimulating hormone (TSH)levels may be used as a screening test. Briefly, thyrotropin-releasinghormone (TRH) prompts the pituitary gland to produce TSH. However, TRHalso prompts the pituitary to release more of the hormone prolactin(PRL). Elevations of PRL can interfere with ovulation by suppressingrelease of the hormones LH and FSH, which stimulate the ovary. Lowlevels of TSH may also interfere with the rate of metabolism of sexhormones, which may also cause ovulatory disorders. Menstrualirregularities and bleeding problems are common in hypothyroid women.

Diagnostic tests for screening analytes, e.g. urinary hormones ormetabolites thereof, may utilize antibodies specific to the analyte. Achange in the level from a predetermined threshold level may be noted bydifferences in color or color intensity compared with the color in areference window or a reference guide. The color change may be producedusing techniques such as enzyme-linked immunosorbent assays or lateralflow color matching assays to indicate the amount of analyte in a urinesample.

Improvements to the diagnostic tests for fertility monitoring have beenmade by removing the step which required the individual to interpret theresults. In these products, electronic sensors and displays provideclear outputs indicating analyte levels. For example, the Clearblue®Easy Fertility Monitor (CBEFM) provides a method for monitoring thefertility status of an individual using two hormones: LH and estrogenwith electronic reading and a digital display. The Clearblue® DigitalOvulation Test (CDOT) is another commercially available device, whichemploys a variable threshold for LH surge determination, and is also animprovement over the color matching visually read tests. Although bothCBEFM and CDOT show improvement over the art, there still remains a needfor such diagnostic devices that are affordable to the average consumerand provide simplicity of use over the prior art. Accordingly,improvements in detection systems are desirable.

SUMMARY

The systems, methods, and devices of the disclosure each have severalinnovative aspects, no single one of which is solely responsible for thedesirable attributes disclosed herein.

A method of detecting a variation in a monitored analyte level in afluid sample from an individual is provided. The method includescollecting a series of samples over a single biological cycle of theindividual, determining a baseline from a plurality of samples in theseries, determining a threshold associated with the monitored analytelevel for the individual based at least in part on the determinedbaseline, generating a signal representative of the monitored analytelevel in one or more samples in the series, comparing the signal to thethreshold, and generating an output based at least in part on a resultof the comparing.

A device for detecting a variation in a monitored analyte level in afluid sample from an individual is provided. The device includes meansfor collecting a series of samples, means for determining a baselinefrom a plurality of samples in the series, means for determining athreshold associated with the monitored analyte level for the individualbased at least in part on the determined baseline, means for generatinga signal representative of the monitored analyte level in one or moresamples in the series, means for comparing the signal to the threshold,and means for generating an output signal in response to the means forcomparing.

A test kit for detecting a variation in a monitored analyte level in afluid sample from an individual is provided. The test kit includes fluidsample collectors and a reader. The reader includes a port for acceptinga fluid sample collector therein and a circuit. The circuit may beconfigured to determine a baseline from a plurality of initial samplesin a series of samples collected with a series of fluid samplecollectors, determine a threshold associated with the monitored analytelevel for the individual based at least in part on the determinedbaseline, generate a signal representative of the monitored analytelevel in one or more samples in the series collected subsequent to theinitial samples, compare the signal to the threshold, and generate anoutput signal based at least in part on the result of the comparing.

Details of one or more implementations of the subject matter describedin this specification are set forth in the accompanying drawings and thedescription below. Other features, aspects, and advantages will becomeapparent from the description, drawings, and claims. Note that therelative dimensions of the following figures may not be drawn to scale.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top perspective view of an example of a reader devicewithout a disposable test stick according to an implementation of theinvention.

FIG. 2 is a top perspective view of an example of a reader device with adisposable test stick according to an implementation of the invention.

FIG. 3 is a top view of an example of a printed circuit board for areader device according to an implementation of the invention.

FIG. 4 is a bottom view of an example of a printed circuit board for areader device according to an implementation of the invention.

FIG. 5 is a diagram of an example of a triphasic test strip suitable foruse in an implementation of the invention.

FIG. 6 is a flow diagram of an example of an implementation of themethod for detecting a variation in a monitored analyte level in a fluidsample from an individual.

FIG. 7 is a flow diagram of an example of the surge thresholdcalculation according to an implementation of the invention.

FIG. 8 is a circuit diagram of an example circuit suitable for use in animplementation of the invention.

DETAILED DESCRIPTION

For many people, having a child provides a life affirming achievement inone's life. Conceiving a child is not by any means an easy task. Withthe rise of expensive fertility clinics to assist in the conceptionprocess, the public demand for scientific methods to help begin theirpath to parenthood is evident. As a low cost alternative, home test kitshave become available. However, these kits may require lengthycalibration periods. These kits may feature results display which isdifficult to read and/or interpret. Furthermore, these kits, in aneffort to simplify the test, may feature a “one-size-fits-all” assaywhich may not be appropriate for the body chemistry of all potentialusers of the kit.

In most cases, diagnostic devices rely on the individual's hormone levelto be either “high” or “low” relative to a fixed threshold value. It hasbeen found that many individual subjects do not conform to the averagein terms of basal circulating hormone levels, cycle length and/or theduration of the cycle. Furthermore, variations can extend from one cycleto another in the same individual, making the use of a fixed thresholdfor the entire population problematic. In the CBEFM device mentionedabove, the user will monitor their urine sample over multiple menstrualcycles. The monitor stores the data, compares readings day to day, andidentifies the days of maximum fertility. Although the CBEFM includessome capability to learn from previous cycles, this feature cannot beeffective for the first cycle. These drawbacks are resolved in theinventive embodiments described herein.

In one implementation, a test kit may include two units, a digitalreader and a package that contains multiple disposable test sticks.Because the test method can be effective in a single cycle, the kit mayinclude only enough disposable test sticks for a single cycle of tests,for example, about 20. The reader may be activated mechanically, morepreferably, activation is achieved by the change of the lightreflectance of the background with or without the test stick. The readermay also be designed to be activated by inserting a single-usedisposable test stick and to measure the color development at thedetection area of the test strip after a urine sample is applied. At thecompletion of the test, the test result may be converted to anelectronic or digital output. The disposable test stick design may bebased on lateral flow technology and contain a test strip with necessaryreagents that allow for the detection of luteinizing hormone (LH),follicle stimulating hormone, human chorionic gonadotropin, estrogen,progesterone, testosterone, or metabolites thereof.

In an implementation for detecting LH surge, ovulation prediction may beachieved by establishing a basal LH level based at least in part onnon-surge urine samples tested during the early phase of the cycle,followed by comparing the LH level of subsequent samples to a thresholdderived at least in part from the basal LH level. In one suchimplementation, the LH surge may detected by detecting an elevated levelof LH based on a threshold which is defined as three times theestablished basal LH levels for that individual. This threshold may betotally unique for each user and cycle, and may be based at least inpart on her individual hormonal levels. With this technique,personalized threshold levels are established for each user and also foreach cycle, improving accuracy and ease of use over existing productsand methods.

FIG. 1 is a top perspective view of a reader device of such a kitwithout a disposable test stick installed. A device 100 may be formedfrom plastic, metal, or other material. The device 100 includes a teststick acceptor port 110. The test strip acceptor port is designed toreceive test sticks for analysis. The device 100 also includes a display120. The display 120 may render various icons or messages to a user suchas test results, device status, or error messages. The display 120 maybe color or monochrome. In an example implementation, the display 120may be a liquid crystal display (LCD). The device may further include atest stick alignment marker 130. In the example shown, the test stripalignment marker 130 is a triangle pointing to the test stick acceptor110. The test stick alignment marker aids with insertion of a test stickinto the device 100. The device 100 may include a test stick ejector140. The test stick ejector 140 may be a manual or electronic mechanismto eject a previously inserted test stick from the device 100.

FIG. 2 is a top perspective view of the reader device of FIG. 1 with atest stick inserted. In the example shown, the device 100 is accepting atest stick assembly 200 housing the actual test strip 210. It isdesirable for the test stick assembly 200 to couple with the device 100so that the test stick assembly 200 will not fall out of the device 100and may form a water resistant seal to protect a portion of the device100 from fluid samples collected via the test stick assembly 200. Thecoupling should also minimize ambient light leakage into the device whentesting is being performed on a test strip. Fluid samples collected viathe test stick assembly 200 are generally urine, although depending onthe test being performed, could be blood, sweat, tears, saliva, or anybodily fluid. An example test strip 210 will be described below inreference to FIG. 5. The test stick assembly includes a test stickhousing 220. In an implementation, the test stick housing 220 may beformed from plastic. The test stick assembly 200 includes a test stickalignment marker 230 corresponding with the test stick alignment marker130 on the device 100. The test stick assembly 200 may also include aclicking sound feature to indicate proper alignment and insertion intodevice 100.

FIG. 3 is a top view of a printed circuit board housed in the readerdevice of FIGS. 1 and 2. The display 120 is coupled with the printedcircuit board 300 using one or more signal lines 320. The printedcircuit board may include one or more input/output (I/O) terminals 330.The I/O terminals 330 may be used to read or write data from a memory(e.g., collected analyte readings, new program instructions, etc.).

FIG. 4 is a bottom view of the printed circuit board of FIG. 3. Theprinted circuit board 300 includes a processor/memory chip 425. Theprocessor chip 425 is coupled with the display 120 and to one or moredata I/O pads for test, data downloads, programming, etc. The memory maybe used to store data received or produced by the processor chip 425.The memory may also be used to store instructions to direct operation ofthe processor chip 425. The printed circuit board 300 may further becoupled to a power source 420. In the example shown in FIG. 4, the powersource is a battery, although any other suitable power source may beused. Discrete components such as resistors and capacitors 410 may alsobe provided on the printed circuit board 300.

The printed circuit board 300 includes one or more sensors 430. In theexample shown in FIG. 4, the printed circuit board 300 includes twooptical sensors 430 a and 430 b. In this implementation, the sensors 430may be phototransistors In other implementations, the sensors 430 may beone or more photodiodes, electroactive sensors or radioactivity sensors.The sensors may be of the same or different types. The sensors 430 arecoupled with the processor chip 425.

The printed circuit board 300 may include an emitter 440. In animplementation including photoelectric sensors 430, the emitter 440 maybe a light source such as a light emitting diode (LED). In animplementation including photoelectric sensors 430, as shown for examplein FIG. 4, the light source 440 may be located equidistant between thephotoelectric sensors 430 a and 430 b. The light source 440 may becoupled with the processor chip 425. The light source 440 may illuminateaccording to a configurable pattern. In an implementation where thelight source 440 is coupled with the processor chip, the illuminationpattern may be controlled by the processor chip 425. In animplementation where the light source 440 is not coupled with theprocessor chip 425, the illumination pattern may be controlled by aseparate timing circuit.

As the emitter 440 illuminates the test strip 210, the sensor 430 maydetect a response from the illumination. For example, in animplementation where the emitter 440 is a light source, thephotoelectric sensor 430 will detect the amount of light reflected bythe test strip 210. An example method of detection will be discussed inmore detail below.

The emitter 440 and sensor 430 may be used to detect the insertion of atest stick. When the reader device is not assembled with a test stick,the emitter in the reader device can turn on periodically, for example,every two seconds. Detection of the presence of a test stick may beachieved by detecting a large difference in sensor response depending onwhether the emitter is on or off due to the presence of the nearbyreflective surface of the test stick. For example, in an implementationincluding two photodiode sensors, four readings may be captured: (1)first sensor output with emitter on, (2) first sensor output withemitter off, (3) second sensor output with emitter on, and (4) secondsensor output with emitter off. In this example, very low andapproximately equal readings for all four indicate that the readerdevice is still in the packaging or sitting on the counter waiting forthe next test to be performed. Readings indicating a high lightintensity at the photodetector for tests 1 and 3 and a low lightintensity at the photodetector for tests 2 and 4 indicate the presenceof a test stick 210. The device 100 may use this information to alteroperation mode (e.g., from low power stand-by mode in the packaging tohigher power test mode when a strip is inserted).

FIG. 5 is a diagram of an example of a triphasic test strip suitable foruse in an implementation of the invention, although it will beappreciated that a wide variety of test strip designs may be used. Thefluid path along the test strip 500 will be discussed starting with thebottom of the figure and moving up. It will be recognized that thisspatial orientation is merely a convenience. At the bottom of the teststrip 500, a fluid sample may be applied. The test strip 500 may beformed from an absorbent material to aid in the uptake of the fluidsample. The fluid sample may encounter a conjugate region 510. In theexample shown, the conjugate region 510 is a colloidal gold antibodyconjugate region where the antibody binds to the analyte of interest(e.g. LH). As the fluid sample passes through the conjugate region 510,analyte in the fluid sample will bind the gold conjugated antibody inthe liquid phase and carry the conjugate-analyte complex along thestrip. The fluid sample may then pass through a second antibody region520. In the example shown, the second antibody region 520 includesbiotinylated antibody that specifically binds to a different epitope onthe analyte of interest than the gold conjugated antibody, forming a“sandwich” of analyte and two antibodies, one with colloidal gold, andthe other with biotin. The sandwich may then be carried further alongthe test strip across a first overlapping region 530. The area from thestart of the test strip 500 to the first overlapping region 530 maygenerally be referred to as the release medium 590.

After the overlapping region 530, the test strip 500 includes anitrocellulose portion 540. As the fluid sample continues along the teststrip 500, the sample next encounters a test line 550. In the exampleshown in FIG. 5, the test line 550 is an avidin test line for bindingthe biotin on the second antibody to trap the sandwich (with the gold)at the test line. The test line 550 will thus become darker as more ofthe sandwich complexes are accumulated. In an example implementationwhere the conjugate comprises colloidal gold, the electronics system,which may include sensors and/or a processor for performing atransformative algorithm on sensed data, may measure the colloidal goldspecifically bound at the test line 550 of the test strip 500. After thetest line 550, the test strip 500 may include a control line 560. Thecontrol line 560 may also generally be referred to as a reference line.When present, the control line 560 includes antibodies or other proteinsthat specifically bind the gold conjugated antibody to provide ameasurement of gold bound antibody in the fluid that is not specificallybound to the analyte. Reflectance measurements from the test line 550and/or control/reference line 560 may be used separately to definesuccessful testing and analyte concentrations. In some embodiments, thereflectance of light from the test line 550 may be compared with thereflectance from the test strip downstream from the test line 550 in aregion where there may or may not be a control/reference line 560 todefine successful testing and analyte concentrations. Strips without acontrol/reference line may be advantageous because it eliminates theneed for the antibodies at this line, reducing cost of the strip.

The nitrocellulose portion 540 may terminate with a second overlappingregion 570. The second overlapping region 570 may serve as a borderbetween the nitrocellulose portion 540 and an absorbent portion 580 ofthe test strip. The absorbent portion 580 of the test strip 500facilitates the uptake of the fluid sample as it arrives at the end ofthe test strip 500.

Test strips of this nature are known in the art, and are described inmore detail in, for example, FIGS. 2-6 and the accompanying descriptionof U.S. Pat. No. 6,319,676, the entire content of which is herebyincorporated by reference.

It may be desirable to align the test strip 500 when inserted into thedevice 100 such that the nitrocellulose region is substantially locatedunder the sensor 430. A first sensor 430 may be located directly overthe test line 550. A second sensor may be located directly over a secondregion of the strip that may or may not contain a control line. Furtherdetails of one embodiment of a sensor 430, emitter 440, and test strip500 alignment are discussed below. Measurements of the reflectivitiesprovide a measure of analyte concentration.

Turning now to analyte change detection methods which may be used by thedevice, FIG. 6 is a flow diagram of an example of an implementation ofthe method for detecting a variation in a monitored analyte level in afluid sample from an individual. At a block 620, a series of samples maybe collected. The samples collected may be, for example, urine samples.Preferably, the series of samples is collected over a single biologicalcycle of the user, for example, over a single menstrual cycle. Thisallows a baseline and threshold to be developed in the same cycle. At ablock 630, a baseline may be determined from a plurality of samples ofthe series collected. The baseline samples may be initial samplescollected over an initial plurality of days of the cycle. For example,samples collected on the first three days after a user's menses may beused to determine a baseline. In an implementation, the samples may becollected on any one or more of the third through the tenth day from theonset of menses of a menstrual cycle of the individual.

At a block 640, a threshold may be associated with the monitored analytelevel for the individual based at least in part on the determinedbaseline. The threshold represents a personalized value for the specificindividual monitoring the analyte level for a current biological statusrather than relying on previously measured cycle information or a fixedthreshold for all individuals. An example of one possible determinationof a baseline and threshold will be described in further detail below inreference to FIG. 7.

At a block 650, a signal may be generated representative of themonitored analyte level in one or more samples. For example, the signalmay be based at least in part on an amount of light reflected by thetest line on the test strip.

At a block 660, the signal may be compared to the threshold. Thecomparison may include detection of a difference between the valuesand/or statistical or probability analyses of the values. At a block670, an output may be generated based at least in part on the comparing.In the case where the signal value exceeds the threshold value, theamount of measured analyte may be higher in the current sample undertest than the threshold value. In an implementation where the analyte is(LH), this condition may correspond with an LH surge for the individualthereby predicting the onset of ovulation. It will be appreciated thatthe method may also detect the inverse case and output a signal if thesignal value for the selected sample falls below the threshold value.For example, in the case where the measured analyte is glucose, it maybe desirable to produce an output at block 670 indicating that themeasured level falls below the threshold thereby indicating a low bloodsugar level. Furthermore, in a competitive assay, for example, a higheranalyte concentration may correspond to a signal value that drops belowa threshold.

In some implementations, the process may include a disable step. In thecase where LH is the monitored analyte, the process may terminate oncean LH surge is detected and a signal indicating the same transmitted,for example, to a display. In an implementation, the disabling may bebased on the number of samples collected. For example, once the processhas collected 20 samples, the process may terminate and the readerdevice disabled.

FIG. 7 is a flow diagram of an example of an implementation of the surgethreshold calculation according to an implementation of the invention.The calculation begins at a block 705. At a block 710, the baseline sumis set to a value of zero. At a block 715, sensor data is collected. Inan implementation where the sensor is a photoelectric sensor, the datacollected is a measure of the amount of light reflected. At a block 720,the sensor data collected at block 715 is used to calculate a numericmeasurement value. At a decision block 725, the calculated numericmeasurement value is compared to an offset coefficient. If themeasurement value is less than the offset coefficient, then the flowcontinues to a block 730. At block 730, since the measurement value isless than the offset coefficient, the flow sets the value at apredetermined minimum, the offset coefficient. At block 730 the baselinesum is set to the previous baseline sum plus the offset coefficient. Ifthe measurement value is greater than the offset coefficient, then theflow continues to a block 740. At block 740, the baseline sum is setequal to the previous baseline sum plus the measurement value. Afterblock 730 or 740, the flow continues to decision block 745. At block745, the flow determines if more readings should be collected. Forexample, the device may be configured to collect three baselinereadings, one per day on each of the first three days after a user'smenses. If more baseline readings are needed, the flow returns to block715. If no additional baseline readings are needed, the flow continuesto a block 750. To a user of the device, a baseline collection versus ananalysis collection may be indistinguishable.

Once the baseline readings have been collected, block 750 sets thebaseline equal to the baseline sum divided by the number of baselinereadings collected. This provides an average reading based on the numberof baseline days. It will be appreciated that other calculation methodssuch as a weighted average, moving average, or calculation methodstaking into account other variables such as user's age, number ofchildren, height, or weight may be used to calculate the baseline. Theflow continues to a block 760 where the surge threshold is set to thebaseline multiplied by a surge factor. For example, in animplementation, a surge factor of three may be desirable. Depending onthe monitored analyte, the surge factor may be configured to differentvalues. For example, in an LH configuration, the surge factor may bethree, while in a progesterone configuration the multiplier may be two.

In an implementation where the surge factor is equal to the number ofbaseline readings, the flow may take an alternative path after block745. In this alternative path, at a block 765 the surge threshold is setto the sum of the baseline readings. In this specific case, the surgefactor times the average baseline reading may be the same as the sum ofthe baseline readings. In some cases, this can reduce the number ofcomputations required.

The flow ends at a block 770 with a calculated surge threshold. The flowmay be implemented as a hardware circuit or as instructions executed bythe processor chip. The calculated surge threshold may be stored by thedevice, for example in memory coupled with or present in the processorchip. In this example, the threshold value calculated at the beginningof a cycle is used to monitor and detect variations during the samecycle.

FIG. 8 is a circuit diagram of a circuit suitable for use in animplementation of the invention. This implementation includesphotodetectors 403 a and 403 b as the sensors. Sensor 430 a may bepositioned substantially over the test line 550 of the test strip.Sensor 430 b may be positioned over a blank region downstream of thetest line on the strip. In this embodiment, no control/reference line ispresent. As described further below, reflectance measurements are madefor these two regions for a time period after a fluid sample is appliedto one end of the strip.

The circuit includes a light emitter 440. The light emitter 440 may bean LED. The light emitter 440 is connected a processing/control circuit806 that may be in the integrated circuit 425. The photodetectors 430 aand 430 b are also each coupled to the processing/control circuit 806 tocontrol initiation of the photodetector operation. The output ofphotodetector 430 a is coupled to capacitor 813, and the output ofphotodetector 430 b is coupled to capacitor 812. The other side of eachcapacitor is grounded. Each capacitor further has a reset switch 817 and816 connected across it to selectively discharge the capacitors. Inoperation, each photodetector output will charge its respectivecapacitor with its output current. The time required to charge eachcapacitor to a defined threshold level is a measure of the photodetectoroutput, and thus is a measure of the reflectivity of the strip in theregion under each photodetector.

The time period to charge the capacitor to the threshold may bedetermined as follows. If photodetector 430 a is being measured, LED 440is switched on, switch 817 is opened, a counter 830 is started, and aswitch 820 is used to connect the high side of capacitor 813 to thepositive input of a comparator 824. The negative input to the comparator824 is coupled to a reference voltage, which is advantageously derivedfrom the battery voltage VDD. For example, the reference voltage may be½ of VDD. The output 832 of the comparator 824 is coupled to a stopinput of the counter 830 that stops the counter 830 when the comparatoroutput goes high. As capacitor 813 is charged by the photodetector 430 aoutput, the voltage on the high side of capacitor 813 increases,increasing the voltage input to the positive input of the comparator824. When this voltage reaches the reference voltage input to thenegative side of the comparator 824, the comparator output 832transitions from low to high. The count value 836, which is a measure ofthe time between counter start at the beginning of the process andcounter stop when the comparator goes high, is fed to the processor 806.In this embodiment, a larger count indicates a longer time for capacitorcharging, indicating a lower photodetector output, and therefore a lessreflective surface under the photodetector. Once a count forphotodetector 430 a is acquired, the switch 817 is closed, and theprocess repeats for photodetector 430 b, switch 816, and capacitor 812,with the switch 820 in the other position.

Collectively, the elements of the processor chip 425 are connected toone side of a power supply 420. Explicit power transmission tracesbetween the elements of the processor chip 425 have been omitted fromFIG. 8. The other side of the power supply 420 is connected to a ground.Integrated circuit 425 may also include a memory 860 for storing dataand instructions as described above.

In operation, the reader 100 detects that a test strip is installed andbegins taking count values for photodetector 430 a (the upstreamphotodetector) and 430 b (the downstream photodetector) at a pollingrate. A rate of once per second for the polling rate has been foundsuitable for reasons that will be described further below. From eachpair of counts, the reader computes a measurement value M defined asfollows:

M=S*((A/B)−(C/D))  Equation 1

Where A=initial downstream count value

B=current downstream count value

C=initial upstream count value

D=current upstream count value

S=constant scale factor

In use of the device, immediately following test strip installation andapplication of a sample, the value of M is near zero, because both areasof the strip under each photodetector have approximately equalreflectances before the sample migrates down the strip to reach thephotodetector regions. Furthermore, the current counts B and D will beabout equal to the initial counts A and C, making M about equal to 1-1which is near zero. When the fluid front of the sample first reaches theupstream detector, the count value D will increase because the strip inthat region becomes less reflective, causing M to increase since A/B isstill near 1, but C/D is now less than 1. The reconstituted gold labeledantibodies and antibody-antigen sandwiches slightly lag the fluid front.When the gold reaches the region under the upstream photodetector, Dincreases further, which further increases the value for M. If antigenis present in the sample, gold labeled antibody-antigen sandwiches willbe captured at the test line 550, stopping their further migration downthe strip. When the fluid front and gold labeled antibodies reach thedownstream photodetector region, this area will darken also, increasingthe count value of B, which decreases the value for M, because A/Bbecomes smaller than 1. As the assay develops further, most of the goldlabeled antibodies that are not part of sandwich complexes and are thusnot captured at the test line 550 migrate past the downstream detectorregion, leaving behind a residual background. After a few minutes, thevalues for B and D stabilize, stabilizing the value for M to a finalvalue. This value for M will be greater than 0 if the reflectance of thetest line is lower than the reflectance of the blank region, whichindicates that gold labeled antibody-antigen sandwiches captured at thetest line 550 exceed the residual background of gold labeled antibodiesin the blank downstream region of the strip (because D will be largerthan B). Higher final values of M indicate higher concentrations ofantigen (e.g. LH) in the sample.

As described above, the reader does not monitor M as a continuousvariable, but rather generates M values at a given polling rate, whichmay be once per second. Sampled values of M may be handled as follows.The first pair of collected counts are used for initial values of A andC, and no value for M is computed. The next pair of samples are used forB and D, which are combined with the A and C counts to produce a valuefor M. The reader waits for up to 10 minutes (600 samples) for the valueof M to exceed a fluid detection threshold. At some points during thisphase, the values of A and C may be replaced with B and D as long as thevalue of M is less than a small threshold, typically a few counts. Thiscan be used to compensate for drift in the battery, led, and sensors.When the value of M exceeds the fluid detection threshold, thisindicates that for this most recent pair of counts, the fluid front hasreached the upstream detector and D has become significantly larger. Ifthe value for M does not exceed the fluid detection threshold for 10minutes (e.g. for 600 samples) the assay may be aborted and an errorsignal may be displayed. Typically, M will exceed the fluid detectionthreshold within a minute after sample application, but a user may delaysample application after installation of the test stick which is whensampling is automatically initiated.

Once the computed value for M exceeds the fluid detection threshold, thevalues for A and C can no longer be reset and are used for all further Mcomputations. Once the fluid detection threshold is exceeded, the readercontinues to compute M at each polling time, and will generally detect acontinually increasing value for M. Because the gold will now tend toquickly increase the D count value, the reader monitors M to determineif M passes a second, higher threshold. In one embodiment, the readerdetects whether M passes the second threshold within seven seconds (e.g.within seven samples) of the sample at which M exceeded the fluiddetection threshold. If the value for M does not exceed the secondthreshold within this time the assay may be aborted and an error signalmay be displayed.

Once the value for M exceeds the second threshold, indicating that theassay is proceeding correctly, the system may continue taking samplesfor an additional five minutes (e.g. 300 more samples) and use the finalcount values at this end point for a final value of M that indicatesantigen concentration. These final values for M can be used as describedabove in FIG. 7 to compute a surge threshold (e.g. the surge thresholdequals the sum of final M values for the first, second, and thirdassays). Subsequently, the final M for each assay can be compared tothis surge threshold to detect a surge in antigen concentration andprovide an output to the user indicating the presence of the surge. Inthis embodiment, the “measurement value” of FIG. 7 is an M value fromEquation 1.

The actual numerical values for M that are produced with this algorithmwill depend on the value selected for the scale factor S and thesensitivity of the assay materials. In one embodiment developed by theapplicants, the scale factor is 666, and the resulting M valuesgenerally range from relatively small negative numbers to 100 or so. Inthis embodiment, the fluid detection threshold may be 20, and the secondthreshold may be 85.

It will be appreciated that a variety of alternative and additionalalgorithms can be used to process count values. For example, it would bepossible to assume the assay was performed correctly, and only sample acount pair upon strip insertion to produce an A and B, wait 10 or 15minutes, and produce a second count pair for B and D, and use theresulting M from equation 1 as the assay result. As additions to theabove described method, the individual count values can be used todetect additional aspects of successful or failed assays. For example,changes in M can be correlated to individual changes in B and/or D toensure that the changes in M are being caused by changes in B and D thatare expected at that point in the assay. Absolute values for the countscan also be used to detect operational errors with the photodetectors orlight source. Count values or M values could also be processed usingaveraging or other statistical methods to reduce noise or enhancecertain signal characteristics that are desired to be detected.

The polling rate may also be changed. With the above algorithm, if thepolling rate is very high, battery life is reduced. On the other hand,if the sampling rate is too low, the changes in M produced as the fluidfront crosses the first and second detector regions could be detectedlate or missed entirely. As noted above, a sampling rate of once persecond has been found suitable.

As another enhancement, M values can be analyzed to detect early LHoutlier readings. For example, if the first three M values are 4, 35,and 6, then the 35 can be discarded as an outlier, and the next computedM value can be used in the baseline computation. Also, if the first fewM values are all very large, such as 50 or 75 or more, the reader candisplay an error code indicating the user should not perform furtherassays in that cycle, assuming that the user did not start the testearly in the cycle, and perhaps was in the midst of a surge when testingbegan.

To test the accuracy of the above described device, urine samples werecollected from test subjects. The urine samples were tested for LHconcentration with a Siemens Immulite 1000 analyzer to produce actual LHconcentration values. The same urine samples were also applied to thedevice described above, and also to the analog “color matching”ovulation detector commercially available as the First Response® DailyOvulation Test. The results are presented in the tables below:

Subject 1: Invention First Response ® Immulite Results EmbodimentDisplay Device Visual Day of Cycle (mIU/ml) Output Results 5 21 NO−Negative 6 30 NO− Negative 7 42 NO− Negative 8 45 NO− Negative 9 44 NO−Negative 10 28 NO− Negative 11 63 NO− Negative 12 23 NO− Negative 13 43NO− Negative 14 143 YES+ Negative 15 173 Positive

Subject 2: Invention First Response ® Immulite Results EmbodimentDisplay Device Visual Day of Cycle (mIU/ml) Output Results 5 13 NO−Negative 6 21 NO− Negative 7 18 NO− Negative 8 40 NO− Negative 9 15 NO−Negative 10 19 NO− Negative 11 40 NO− Negative 12 18 NO− Negative 13 26NO− Negative 14 28 NO− Negative 15 53 YES+ Negative 16 181 Positive

Subject 3: Invention First Response ® Immulite Results EmbodimentDisplay Device Visual Day of Cycle (mIU/ml) Output Results 5 5 NO−Negative 6 6 NO− Negative 7 7 NO− Negative 8 5 NO− Negative 9 7 NO−Negative 10 6 NO− Negative 11 5 NO− Negative 12 6 NO− Negative 13 11 NO−Negative 14 65 YES+ Positive

The above examples illustrate the varying levels of baseline LHconcentration in different subjects. Furthermore, it can be seen thatfor women with an existing elevated level of LH, e.g. more than about 20mIU/ml early in the menstrual cycle, the invention embodiment readerpredicts the LH surge a day earlier than the analog First Response®prior art product. This can be attributed to the use of a personalizedbaseline as described above. This single day of advance detection issignificant, and can mean the difference between a pregnancy or nopregnancy in a given cycle.

It will be appreciated that the above described system could be used todetect analytes other than hormones, with especially advantageousapplication in any environment where samples are collected, and thediagnostic test may be interpreted according to a photosensitivereading. For example, variation of the monitored analyte may be used toindicate an onset of menopause (e.g., natural menopause, perimenopause,induced menopause, premature menopause, or post menopause) or ovarianreserve for the individual. In an implementation, variation of amonitored analyte such as progesterone may be used to indicate an onsetof an abnormal pregnancy (e.g., failed implantation, ectopic pregnancy)for the individual. In an example progesterone implementation, a normalpregnancy is detected if the progesterone level is greater than thethreshold value while levels equal to or less than the thresholdindicate an abnormal pregnancy. The detection method or device may beincluded in a test kit such as an ovulation detector test kit sensing LHin urine samples from an individual.

As used herein, the term “determining” encompasses a wide variety ofactions. For example, “determining” may include calculating, computing,processing, deriving, investigating, looking up (e.g., looking up in atable, a database or another data structure), ascertaining and the like.Also, “determining” may include receiving (e.g., receiving information),accessing (e.g., accessing data in a memory) and the like. Also,“determining” may include resolving, selecting, choosing, establishingand the like.

As used herein, a phrase referring to a list of items refers to anycombination of those items, including single members. As an example, “atleast one of: a, b, or c” is intended to cover: a, b, c, a-b, a-c, b-c,and a-b-c.

The various operations of methods described above may be performed byany suitable means capable of performing the operations, such as varioushardware and/or software component(s), circuits, and/or module(s).Generally, any operations illustrated in the Figures may be performed bycorresponding functional means capable of performing the operations.

The various illustrative logical blocks, modules and circuits describedin connection with the present disclosure may be implemented orperformed with a general purpose processor, a digital signal processor(DSP), an application specific integrated circuit (ASIC), a fieldprogrammable gate array signal (FPGA) or other programmable logic device(PLD), discrete gate or transistor logic, discrete hardware componentsor any combination thereof designed to perform the functions describedherein. A general purpose processor may be a microprocessor, but in thealternative, the processor may be any commercially available processor,controller, microcontroller or state machine. A processor may also beimplemented as a combination of computing devices, e.g., a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or any other suchconfiguration.

In one or more aspects, the functions described may be implemented inhardware, software, firmware, or any combination thereof. If implementedin software, the functions may be stored on or transmitted over as oneor more instructions or code on a computer-readable medium.Computer-readable media includes both computer storage media andcommunication media including any medium that facilitates transfer of acomputer program from one place to another. A storage media may be anyavailable media that can be accessed by a computer. By way of example,and not limitation, such computer-readable media can comprise RAM, ROM,EEPROM, CD-ROM or other optical disk storage, magnetic disk storage orother magnetic storage devices, or any other medium that can be used tocarry or store desired program code in the form of instructions or datastructures and that can be accessed by a computer. Also, any connectionis properly termed a computer-readable medium. For example, if thesoftware is transmitted from a web-site, server, or other remote sourceusing a coaxial cable, fiber optic cable, twisted pair, digitalsubscriber line (DSL), or wireless technologies such as infrared, radio,and microwave, then the coaxial cable, fiber optic cable, twisted pair,DSL, or wireless technologies such as infrared, radio, and microwave areincluded in the definition of medium. Disk and disc, as used herein,includes compact disc (CD), laser disc, optical disc, digital versatiledisc (DVD), floppy disk and blu-ray disc where disks usually reproducedata magnetically, while discs reproduce data optically with lasers.Thus, in some aspects computer readable medium may comprisenon-transitory computer readable medium (e.g., tangible media). Inaddition, in some aspects computer readable medium may comprisetransitory computer readable medium (e.g., a signal). Combinations ofthe above should also be included within the scope of computer-readablemedia.

The methods disclosed herein comprise one or more steps or actions forachieving the described method. The method steps and/or actions may beinterchanged with one another without departing from the scope of theclaims. In other words, unless a specific order of steps or actions isspecified, the order and/or use of specific steps and/or actions may bemodified without departing from the scope of the claims.

Thus, certain aspects may comprise a computer program product forperforming the operations presented herein. For example, such a computerprogram product may comprise a computer readable medium havinginstructions stored (and/or encoded) thereon, the instructions beingexecutable by one or more processors to perform the operations describedherein. For certain aspects, the computer program product may includepackaging material.

Further, it should be appreciated that modules and/or other appropriatemeans for performing the methods and techniques described herein can bedownloaded and/or otherwise obtained by a user terminal and/or basestation as applicable. For example, such a device can be coupled to aserver to facilitate the transfer of means for performing the methodsdescribed herein. Alternatively, various methods described herein can beprovided via storage means (e.g., RAM, ROM, a physical storage mediumsuch as a compact disc, or floppy disk, etc.), such that a user terminaland/or base station can obtain the various methods upon coupling orproviding the storage means to the device. Moreover, any other suitabletechnique for providing the methods and techniques described herein to adevice can be utilized.

It is to be understood that the claims are not limited to the preciseconfiguration and components illustrated above. Various modifications,changes and variations may be made in the arrangement, operation anddetails of the methods and apparatus described above without departingfrom the scope of the disclosure.

While the foregoing is directed to aspects of the present disclosure,other and further aspects of the disclosure may be devised withoutdeparting from the basic scope thereof.

What is claimed is:
 1. A device for detecting a variation in a monitoredanalyte level in a fluid sample from an individual, the devicecomprising: means for collecting a series of samples over a singlebiological cycle of the individual; means for determining a baselinefrom a plurality of samples in the series; means for determining athreshold associated with the monitored analyte level for the individualbased at least in part on the baseline; means for generating a signalrepresentative of the monitored analyte level in one or more samples inthe series; means for comparing the signal to the threshold; and meansfor generating an output signal in response to receiving a comparisonresult from the means for comparing.
 2. The device of claim 1, whereinthe means for collecting a series of samples comprises a plurality oftest strips.
 3. The device of claim 1, wherein the means for determininga baseline comprises a baseline analysis circuit.
 4. The device of claim3, wherein the baseline analysis circuit comprises a photodetector. 5.The device of claim 1, wherein the means for determining a thresholdcomprises a threshold conversion circuit.
 6. The device of claim 1,wherein the means for generating a signal representative of themonitored analyte level comprises a photodetector.
 7. The device ofclaim 1, where the means for comparing the signal with the thresholdcomprises a comparator circuit.
 8. The device of claim 1, comprising adisplay configured to present the output signal to a user.
 9. A test kitfor detecting a variation in a monitored analyte level in a fluid samplefrom an individual, the test kit comprising: disposable test sticks; anda reader, the reader comprising: a port for accepting a test sticktherein; and a circuit configured to: determine a baseline from aplurality of initial samples in a series of samples collected with aseries of test sticks; determine a threshold associated with themonitored analyte level for the individual based at least in part on thedetermined baseline; generate a signal representative of the monitoredanalyte level in one or more samples in the series collected subsequentto the initial samples; compare the signal to the threshold; andgenerate an output signal based at least in part on a result of thecomparing.
 10. The test kit of claim 9, wherein the test sticks comprisetest strips.
 11. The test kit of claim 9, wherein the reader comprisesan optical sensor.
 12. The test kit of claim 9, wherein the threshold isan average of a plurality of monitored analyte measurement values timesa multiplication factor.
 13. The test kit of claim 12, wherein themultiplication factor is three.
 14. The test kit of claim 9, wherein thethreshold is approximately three times the baseline.
 15. The test kit ofclaim 9, wherein the plurality of initial samples consists of threesamples.